1 Description
2 Mask and Parameters
- 2.1 General Parameters
- 2.2 Generation Parameters
- 2.3 Initial Values
3 Inputs, Outputs and Signal Available for Monitoring
- 3.1 Inputs
- 3.2 Outputs
4 Acknowledgements
5 Reference

Description

The Renewable Energy Generator/Converter – Type B (REGC_B) is a WECC standard dynamic model used to represent the converter-level behavior of inverter-based resources (IBRs) such as photovoltaic (PV) plants, wind power plants (Type 3/4), and battery energy storage systems (BESS) in positive-sequence stability studies. The model represents the fast current execution dynamics of the power electronic converter, assuming that inner switching dynamics are much faster and therefore abstracted.

REGC_B executes active and reactive current commands provided by the electrical controller (e.g., REEC) using fast dynamics and rate limits. An active power rate-limiting function is included in the current execution path. The parameter RateFlag determines whether the rate-limit parameter rrpwr is applied as an active current rate limit or as an active power rate limit. These dynamics represent the converter’s ability to track commanded current references while limiting the rate of change of the injected currents.

Based on the commanded currents, measured terminal voltage, and a fixed interface impedance, REGC_B computes equivalent internal dq voltage components and generates three-phase voltage references (Va_ref, Vb_ref, Vc_ref) that drive a controlled voltage source, resulting in the desired current injection into the network. The resulting converter terminal voltage is provided at the output port Vabc and is applied directly to the network.

Mask and Parameters

General Parameters

REGC_B diagram

Name	Unit	Description	Variable = {Possible Values}

Name	Unit	Description	Variable = {Possible Values}
Iqrmax		Rate limit on reactive current recovery after a fault if the initial reactive current is positive (injecting into the grid)	1 ~ 999
Iqrmin		Rate limit on reactive current recovery after a fault if the initial reactive current is negative (absorbing from the grid).	-1 ~ -999
RateFlag		Rate limit flag to determine whether Rrpwr is an active current rate limit or an active power rate limit	0: Rrpwr is an active current rate limit 1: Rrpwr is interpreted as an active power rate limit
Tg	s	Converter controls delay emulation time constant	0.017 ~ 0.05, typical 0.02
Te	s	Converter firing delay emulation time constant	0.005 ~ 0.02, typical 0.0083
Tfltr	s	Voltage measurement transducer filter time constant	0.017 ~0.05, typical 0.02
Rrpwr	pu/s	Rate limit on active power recovery rate after a large voltage dip, or sudden change in active power command	1 ~ 20, typical 10
Imax	pu	Maximum converter current limit	Needs to be consistent with the associated REEC model

PLL parameters

For the EMT implementation, the REGC_B block contains a PLL that is used during the dynamic simulation. The user can configure the PLL parameters.

Name	Unit	Description

Name	Unit	Description
Ki		PI controller integral gain
Kp		PI controller proportional gain
Kd		PI controller derivative gain
Minimum frequency	Hz	Minimum expected frequency of the PLL input signal. This value cannot be modified during the simulation
Filter natural frequency	Hz	Second-order low-pass filter cut-off frequency
Filter damping ratio		Second-order low-pass filter damping (zeta)
Rate limiter	Hz/s	Rate limiter for frequency

Generation Parameters

Name	Unit	Description

Name	Unit	Description
Sbase	VA	Base power (total)
Vbase	V	Base voltage (rmsLL)
Re	pu	Equivalent source resistance
Xe	pu	Equivalent source reactance
Frequency	Hz	Base frequency

Initial Values

Name	Unit	Description

Name	Unit	Description
Initial terminal voltage	V	Initial terminal voltage magnitude, which could be obtained from the load flow
Initial terminal voltage angle	degree	Initial terminal voltage angle, which could be obtained from the load flow
Initial active power	W	Initial terminal active power, which could be obtained from the load flow
Initial reactive power	VAR	Initial terminal reactive power, which could be obtained from the load flow

Inputs, Outputs and Signal Available for Monitoring

Inputs

Name	Unit	Description

Name	Unit	Description
Iqcmd	pu	Reactive current command, from REEC block
Ipcmd	pu	Active current command, from REEC block
Qgen0	pu	Initial reactive power from load flow
Vt	pu	Terminal voltage magnitude measured at the POC

Outputs

Name	Unit	Description

Name	Unit	Description
Vabc	V	Three-phase network output
Freq_diff	Hz	Frequency differences between the terminal frequency and the system frequency
V_t	pu	Terminal voltage
P_t	W	Terminal active power
Q_t	var	Terminal reactive power

Acknowledgements

The development of the REGC_B block in the Smart Inverter Control Library is a contribution of CanmetENERGY at Natural Resource Canada.

Reference

[1] Model User Guide for Generic Renewable Energy System Models, EPRI, October 2023.